1. Field of the Invention
The present invention relates to generally to systems and methods for providing reduced pressure treatment to tissue, particularly open wounds. The present invention relates more specifically to systems and methods for improving the connection between a tissue dressing and reduced pressure source instrumentation used in conjunction with reduced pressure wound treatment (RPWT).
2. Description of the Related Art
Various therapies have been developed over time to facilitate the process of wound closure and healing. Wound closure generally involves the inward migration of epithelial and subcutaneous tissue adjacent the wound. This migration is ordinarily assisted by the inflammatory process, whereby blood flow is increased and various functional cell types are activated. As a result of the inflammatory process, blood flow through damaged or broken vessels is stopped by capillary level occlusion, whereafter cleanup and rebuilding operations may begin. Unfortunately, this process is hampered when a wound is large or has become infected. In such wounds, a zone of stasis (i.e. an area in which localized swelling of tissue restricts the flow of blood to the tissues) forms near the surface of the wound.
Without sufficient blood flow, the epithelial and subcutaneous tissues surrounding the wound not only receive diminished oxygen and nutrients, but are also less able to successfully fight bacterial infection and, thus, less able to naturally close the wound. Additionally, some wounds harden and inflame to such a degree that closure by stapling or suturing is not feasible. Examples of wounds not readily treatable with staples or suturing include large, deep, open wounds; decubitus ulcers; ulcers resulting from chronic osteomyelitis; and partial thickness burns that subsequently develop into full thickness burns.
As a result of the shortcomings of mechanical wound closure devices, methods and apparatus for draining wounds by applying continuous and/or periodic reduced pressures have been developed. When applied over a sufficient area of the wound, such reduced pressures have been found to promote the migration of epithelial and subcutaneous tissues toward the wound. In practice, the application to a wound of reduced pressure typically involves the mechanical-like contraction of the wound with simultaneous removal of excess fluid. In this manner, RPWT augments the body's natural inflammatory process while alleviating many of the known intrinsic side effects, such as the production of edema caused by increased blood flow absent the necessary vascular structure for proper venous return.
Vacuum or reduced pressure induced healing of open wounds has recently been popularized by Kinetic Concepts, Inc. of San Antonio, Tex., through its commercially available RPWT systems product line. The reduced pressure induced healing process has been described in commonly assigned U.S. Pat. No. 4,969,880, issued on Nov. 13, 1990 to Zamierowski, as well as in its related patents, including U.S. Pat. No. 5,100,396, issued on Mar. 31, 1992; U.S. Pat. No. 5,261,893, issued on Nov. 16, 1993; and U.S. Pat. No. 5,527,293 issued Jun. 18, 1996, the disclosures of which are each incorporated herein by reference. Further improvements and modifications of the RPWT process are also described in U.S. Pat. No. 6,071,267, issued on Jun. 6, 2000 to Zamierowski and U.S. Pat. Nos. 5,636,643 and 5,645,081 issued to Argenta et al. on Jun. 10, 1997 and Jul. 8, 1997 respectively, the disclosures of which are each incorporated by reference as though fully set forth herein. Additional improvements have also been described in U.S. Pat. No. 6,142,982, issued on May 13, 1998 to Hunt, et al.
One important component of a RPWT system is the device or structure that connects the reduced pressure source (a vacuum pump, typically) to the components (a granular foam layer, typically) enclosed within the pad or wound dressing. This reduced pressure port structure must adhere to the wound dressing and be in fluid communication with the foam layer of the dressing. The port is preferably of low profile, in the nature of an attachment pad, in order to provide both comfort and safety to the patient. Various efforts have been made in the past to provide suitable adapter configurations to effectively connect the reduced pressure source (through tubing, typically) to a tissue site.
Commensurate with the application of continuous and/or periodic reduced pressures to a wound is a coordinated monitoring of the pressure present at the tissue site as a result of the application of the RPWT system. It has become important, therefore, to provide systems that are capable of monitoring and responding to changes in the level of reduced pressure applied at the tissue site. Various regimens of RPWT that involve cycling the reduced pressure applied to the wound have been found to be beneficial under certain circumstances. Other situations benefit from a constant but closely regulated application of reduced pressure. In any case, it becomes valuable to accurately monitor the level of reduced pressure applied at the tissue site.
Generally it is not possible to characterize the pressure level at the tissue site by simply measuring the level of reduced pressure that the reduced pressure source is providing, either at the source or in the conduit lines connecting the source to the wound dressing. Fluid flow within the primary lumen of tubing associated with RPWT systems prevents using pressure level measurements at the instrumentation from being accurate indicators of the level or stability of the pressure at the tissue site itself. Other methods for directly monitoring the wound pressure levels are therefore required.
Some efforts have been made in the past to provide a separate pressure sensing or measurement conduit to the wound site connected to monitoring instrumentation. These efforts have typically provided a separate lumen within the RPWT tubing or have utilized a separate section of tubing altogether. The assumption being made with such systems, however, is that the ancillary measurement lumen or measurement tube is open and clear down to its port at the wound dressing. This is not always a valid assumption as, despite the fact that the measurement lumen is not forcibly drawing fluids in as is being done in the primary flow lumen of the RPWT system, it still collects fluids and other materials that inhibit or altogether block its function. The typically smaller cross-section of such measurement lumens may reduce the port size, and therefore the chance of fluid or other matter entering the port, but the same smaller cross-section results in even minor blockages becoming significant.